Carrier-wave transmission



J S JAMMER CARRIER WAVE TRANSMISSION Original Filed July 25. 1925 Low Feb. 7, 1928.

I'll Il ill! Patented Feb. '7, 1928.

UNITED STATES PATENT OFFICE.-

JACOB s. JAIYIMER, or SYDNEY, new sourn: warns, AUSTRALIA, ASSIGNOR T WEST- ERN ELECTRIC, COMPANY, INCORPORATED, OF NEW YORK,

OE NEW YORK.

N. Y., A CORPORATION GARRIER-WAVE TRANSMISSION.

Original application filed July 25, 1923, Serial No. 653,629, patented December 21, 1926, No. 1,611,350.

v Divided and thisapphcation filed. November 20, 192.6. Serial No. 149,780.

This invention relates to carrier wave transmissiornand is a division of application, Serial No. 653,629, filed July 25, 1923, patented December 21, 1926, No. 1,611,3 50.

An object of the invention is to provide in a multiples carrier signaling system eflicient intercommunicating means between the terminal and repeater stations.

Another object of the invention is to pro vide intercommunicating means between the terminal and repeater stations of a trans mission system which will inno wise be affected by or affect the operation of the repeaters. v

lrccording to the invention, the terminal and repeater stations of a carrier wave sig: naling system are provided with sending and receiving apparatus for affording intercom: munication between any two or all of said stations. Suchintercomnmnicating apparatus operates with carrier current '01"? frequency diflerentirom that; employed 1n the usual signaling channels and entirely 1n dependentlyfiof the repeaters and the carrier wave transmission apparatus of the usual channels of .thesystema Other .features and aspects of the invention are described hereinafter.

The invention will be. described as applied to a multiplex carrier Wave transmission system, although it .Willbe understood that it isnot limited to such a systemsince some of the features thereof may find application in other forms of signaling systems and in other fields.

The'drawing is a diagrammatic illustration of a multiplex carriertelephone and telegraph system embodying the invention.

The system shown in the drawing comprises in general a main high frequency transmission line ML extending between. the west'terminal and one or more repeater stations R; The usual east terminal which is identical to thewest terminal shownin the drawing, is omitted forj'the sake of simplidyirigthe showing.

The telephone channels employ different carrier frequencies, thoseused :for trans- IIHISSIOH 111 one direction belnggrouped-ina different trequency range those em-.-

ployed for transmission in th e opposite direc manner disclosed and claimed in my pending application, Serial No. 149,77 9, filed tion. The telegraph channels are superimposed upon the telephone channels 1n the November 20, 1926, the telegraph channels employing the same carrier frequenmesw An lntercommumeating channel .10 for communication between the repeater and terminal stations is associated, with the multiplex carrier telephone and telegraph are connected to the main line ML. Telephone channel No. 1 includes a tral'ismitting channel TC and a rece1v1ng channel RC 'which are conjugately-related to a low frequency l ne L by means of a transformer 5 and a balancing network N. The telephone: line L usually extends to and terminates ata telephone switchboard (not shown).

Thetransmitting channel TC includes a modulator M and a. transmitting band filter TBF- Carrier current of the. frequency assigned to this channel is supplied to the modulator M from a high frequency source 0 1 Band filter vTBF is designed to pass currents ofthe carrierfrequency as-- signedto this channel and currentsoffrequencies within either the upper or lower side 'banclt-hereofandto suppress currents of all other frequencies.

In order that the telegraph channel may,

nel, there" is associated therewith a, tele graph transmitting key 6which, during. the

operation thereofis adapted to intermittently shunt an,impedanceelementY, which may take the form] of a non iuductive resistance, across; the leads .tr0m.the source' 01.

ill)

.be superimposed upon thistelephone chanhigh frequency current-.0 Thus, during the intermittent operation of the transmitting key ,6, the amplitude of the carrier current supplied to the modulator M is "alter V cuit of the sounder 9 closed.

nately reduced from and restored to its normal value. Consequently, the telephone signal modulated carrier current output from the modulator M, intermittently changed in amplitude during the transmission of telegraph signals.

The receiving channel RC, includes a re ceiving band filter REF a demodulator DM an amplifier A a low frequency band filter LBF, a high frequency band filter HBF, a rectifier R and a telegraph receiving relay 8 which controls the usual telegraph sounder 9. The receiving band filter R-BF is designed to pass currents of the carrier frequencyassigned to this channel and of the frequencies within either the upper or lower side band thereof and to suppress currents of all other frequencies.

The low frequency band filter LBF is designed to pass currents within the voice range between about 200 and 2000 cycles frequency and to suppress currents of higher frequencies as Well as the telegraph signals below 200 cycles. 1 The high frequency band filter HPF is designed to pass currents of the carrier frequency assinged to this channel and of frequencies within both or one of the telegraph side bands and to suppress currents of all other frequencies. Thus, these two filters separate the received telephone and telegraph signals. 7

The operation of the system in so far as transmission and reception of telephone signals are concerned is well known. Therefore,

no description thereof will be given. The operation of the telegraph channel superimposed upon the telephone channel, which is disclosed and claimed in my copending application mentioned above, Will be referred to briefly.

hen the telegraph key 6 is open, the normal amount of carrier current is flowing to the line and the amount of rectified current through the telegraph receiving relay 8 at the distant station is suiiicient to hold its contactclosed, thereby maintaining the cir lVhen the telegraph key 6 is closed, the amout of carrier current fed to the line reduced and the amount of rectified current through the receiving relay 8 at the distant station is re duced to such an extent that the relay can no'longer hold up its armature. The circuit of the sounder 9 is therefore opened. lVhen the telegraph key 6 is again opened, the

amount of rectified current through the receiving relay 8 at the distant terminal increases and it thereupon closes its cont-act, causing the energiaation of the sounder 9.

The intercommunioating channel TC is connected to the main line ML through a selective circuit- ICF, which may be either an ordinary tuned circuit comprising capacity and-inductance or. aband :filterct' the type disclosed in United States patents to (lampbell Nos. 1,227,113 and 1,227,114, issued May 22, 1917. If the selective circuit is a band filter it should be designed to pass currents of the frequency assigned to this channel and currents of the frequencies within one or both side bands thereof and to suppress: currents of all other fl'ttllltlflfltr.

The intercommunicating channel 1C has associated therewith at each terminal station a transmitting channel TIC and a receiving channel RIC. The transmitting channel TIC includes a high frequency source, such as an oscillator 10, supplying current of the carrier frequency assigned to this channel. The output circuit of the oscillator is connected to the primary of a transformer ll) whose secondary terminates in normally open contacts. The connection of the oscillator 10 to the main line is controlled by t relay 11 having in its operating circuit normally open transmitting key 12.

The receiving channel RIC includes. an input transformer 13, a rectifier IR, and a receiving relay 14; which controls the opera tion of a sounder 15.

Each repeating station It is provided with a repeater having two asymmetric repeating channels Riv and RE for re )eatin currents in opposite directions, and the transmitting and receiving apparatus for the intercomniiinicating channel.

The repeater per so, which forms no part of the present invention, may be of the type disclosed in United States patent to Raibourn No 1,-113357, April '18, 1922, or of the type disclosed in my eopending application, Serial o. 640,643, filed May 22, 1923.

Each of the repeating channels includes an input filter, an amplifier, and an outpunt liltcr, for further details of which reference should be made to either the Raibourn patent or to my said copending application, Serial No. 640,643, filed May 22, 1923.

The transmitting and receiving apparatus for the intcrcomniunieating channel is connected in shunt with the repeating channels through selective circuits 'WICF and EICF so as not to be affected by or ailect the operation of the repeater. Apparatus is provided for receiving signals from either direction over the line. Thus. sic nals transmitted over the intercoinmunieating channel from the west line section are received by a rectifier lVl-t. having a re lay 16 in its output circuit, and the signals incoming from the east line section are re ceived by a rectifier ER which has in its output circuit a relay 17; The rectifier R is connected to the main line ML through in put transformer 18, normally closed contacts of relay 1'9 and selective circuit .VICF. Like- Wise, rectifier ER is connected to' the main line through input.t-ransfor1ner 20, normally closedcontactsof relay 22- and selectivecircuit EICF. The selective circuits .VICF

and EICF are similar to the selective circuit IQF described in connection with the terminal apparatus and perform the same functions.

' sounder 28.

The operation of the receiving relay 16 causes the operation of relays 21 and 22. The operation of the relay 21 causes the operation of thetelegraphsounder 23. The operation of relay 22 disconnects the recti tier ER from the east line section, and connects to this line section a source of high frequency current 10, of. the carrier fre quency assigned to the intercommunicating channel.

lVherrthe receiving relay 17 operates it causes the operation of relays 25 and 19. Relay 25 controls the operation of the The operation of relay 19 disconnects the rectifier VB from the line,and connects to the line the high frequency source 10 The load on the oscillator 10 is always constant due to the provision of resistances 2a and 26 connected through closed contacts of relays 22 and 19, respectively, to the oscillator. then either relay operates, its associatedresistance is disconnected from the oscillator and one of the line sections substituted therefor.

The apparatus for the intercoimnunicatiug channel at each repeater station includes also a telegraph key 27 and a relay 28, whose actuation causes the energization of relays l9 and 22 whereby the source of high frequency current 10 is connected to both sections of the transmission line outgoing from the repeater station. 7

The attendant at thewest terminal station desiring to communicate with the attendant at any or all of the repeater stations or with the attendant at "the distant terminal station may do so by actuating transmittingkey 12 to transmit a carrier wave modulated in accordance with a telegraph signal. vUpon the closure of the key, relay ll'operates, connecting the source of high frequency currents 10 to the main line through the selective circuit ICF. The currents so impressed upon the line are selected at the first repeater station by the selective circuit VVICF, and pass through the primary winding of transformer 18. The resulting induced currents in the secondary of this transformer are impressed upon the rectifier R and the rectified current in the output circuit thereof causes the operation of relay 16. Relay 16, in operating, causes the energization of relay 21 which operates the sounder 23. Relay 22 also operates, disconnecting rectifier ER from the line section and connecting thereto the source of high frequency currents 10 Current so impressed upon the line section from the source 10 is selected by the selective circuit WICF at the next repeater sta-- tion on the line where the apparatus functions in the manner previously described.

Thus, the telegraph signals are relayed from station to station and cause the operation of the sounder at each ofethe repeater stations and the sounder at the distant terminal station corresponding to the sounder15 at the west terminal station shown in the drawing.

comprising transmission line sect-ions over which carrier waves of differentfrequencies are transinitted in both directions, a repeater connecting said line sections and including individual paths for repeating waves transmitted in each direction, means for impress ing signaling impulses on one of said line sections at a point remote fromsaid repeater, asource of sustained oscillations at said repeater, and means at said repeater responsive .to signaling impulses incoming over one of said line sections to connect said source to the other line section to repeat said impulses.

2.,A carrier wave transmission system comprising transmission line sections over which speech modulated carrierfwaves of different frequencies are transmitted in both directions, a repeaterconnecting said line sections and including individual paths for repeating waves transmitted iii-each direction, means for impressing telegraph signals on said line sections at points remote from :said repeater, means at said repeater for receiving said telegraph signals, a source of sustained oscillations at said repeater, and meansat said repeater responsive to tele graph signals incoming over either ofsaid line sections to connect said source to the other line section torepeat said telegraph signals. M I i j 3. A carrier wave transmission system comprising transmission line sections over which carrier waves ofdifferent frequencies are transmitted in both directions, a repeater connecting said. line sections and including individual paths for repeating waves transmitted in each direction, means for impressing signaling impulses on one of said line sections at a point remote from said repeater,

a source of sustained oscillations at} said u,

repeater, means at said repeaterresponsive to signaling impulses incoming over one of said linesectionsto connect said source to the other line section to repeat said impulses, a transmitting device at saidrepeater, and

lllt) means operated by said device toconnect said source of oscillations to both line sections.

4. A carrier wave transmission system comprising transmission line sections over which speech modulated carrier waves of differentfrequencies are transmitted in both directions, a repeater connecting said line sections and including individual paths for repeating waves transmitted in each direc tion, means for impressing telegraph. signals on said line sections at points remote from said repeater, a channel at said repeater for selectively transmitting said telegraph signals, means associated with said channel for receiving said telegraph signals, a source of sustained oscillations of the frequency of said telegraph signaling channel at said repeater, means at said repeater responsive to telegraph signals incoming over either of said line sections to connect said source to the other line section to repeat said telegraph signals, a transmittingdevice at said repeater, and means operated by said device to connect said source of oscillations to both line sections.

5. A carrier wave transmission system comprising atransmission line section, geographically separated terminal and re peater stations connected to said line sections, two one-way repeating paths at said repeater station including amplifiers for repeating the oppositely directed carrier waves, and means associated with said line sections for communicating between the terminal. and repeater stations, said means including a carrier current channel, a source of high frequency current at each station, means at each station for connecting said source to an outgoing line section, a signaling device at said terminal station responsive to current from said source at said repeater station, a signaling device at said repeater station responsive to current transmitted from said terminal station, and means at the repeater station responsive to current incoming over one line section from said terminal station to connect the same source of high frequency current at said repeater station to the other line section.

6. A carrier wave transmission system comprising a terminal station, transmission line sections over which carrier waves of different frequencies are transmitted in both directions, a repeater station connecting said line sections and including individual paths for repeating Waves transmitted in each direction, a source of high frequency currents at said terminal station, means at said terminal station for connecting said source to the line section extending therefrom, a source of high frequency current at said repeater station, a signaling device at each station, and means at said repeater station responsive to current incoming over one line section from said terminal station to cause the operation of the signaling device at said repeater station and to connect the source of high frequency current thereat to the other line section.

7. A- carrier Wave transmission system comprising a terminal station, transmission line sections over which a plurality ofcarrier wavesof different frequencies are transmitted in both directions, a repeater station connecting such line sectionsand including individual paths for repeating waves transmitted in each direction, an intercommunieating channel associated with said system, a source of high frequency currents for said channel located at each station, means at said terminal station to connect the source of high frequency currents thereat to the line section extending therefrom, a signaling device at each station, meansat the repeater station responsive to current transmitted over the intercommunicating channel of one line section from said terminal station for controlling the operation of the repeater station signaling device and the connection of the repeater station current source to the other line section, and means at said terminal station responsive to current'ineoming from said repeater station for controlling the operation of the associated signaling device.

In witness whereof, I hereunto subscribe my name this 11th day of October A. 1).,

JACOB S. JAMMER. 

